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Yup those questions are a stretch for me too! Love that though.

Where are the pivot and unpivot questions?

Hmm, haven't seen those a ton at work / in interviews! Would love to see some examples though if you have any.

Mode's SQL tutorial uses SUM(CASE ...) and CROSS JOIN to mimic pivots: https://mode.com/sql-tutorial/sql-pivot-table/

I think they're specific to Oracle and SQL Server. It's a pity because they can be very useful.

PostgreSQL can do it via the tablefunc extension and there's `\crosstabview` which is built into psql.